Sheet compiler for use in a finisher, such as used with a printing apparatus

ABSTRACT

In a high-speed copier or printer, a set of sheets is occasionally withheld while a finisher performs an operation such as compiling and stapling. When the operation of the finisher resumes, a set of buffered sheets is conveyed as a stack into a sloped compiler tray. An upper compiler member, such as a flapper, pushes the top sheet of the stack toward the backstop of the compiler tray, while a lower compiler member pushes the bottom sheet of the stack toward the backstop of the compiler tray. In this way, all of the sheets are aligned against the backstop, such as for stapling.

TECHNICAL FIELD

The present disclosure relates to a “finisher,” such as for compiling and stapling of sheets, as would be used in, for example, a high-speed digital printing apparatus.

BACKGROUND AND PRIOR ART

In printers and copiers of a certain speed and print volume, it is common to provide a “finisher,” which performs various functions on sheets after the sheets receive printed images thereon. Typical finisher functions include folding and hole-punching, but the most common finisher functions are compiling and stapling a set of sheets, such as would form a multi-page document.

A typical arrangement for a compiler-stapler portion of a finisher includes an uphill-sloped compiler tray, which defines a wall or backstop at the lower edge thereof. Sheets received from a print engine are caught in the compiler tray and align by gravity against the backstop. The backstop thus holds the sheets until all of the sheets are collected in the compiler tray, at which time the stack of sheets against the backstop may be stapled. The now-stapled set of sheets is then ejected from the compiler tray, such as into an output tray.

U.S. Pat. Nos. 5,289,251 and 6,666,444 show examples of such a compiler-stapler, of a design including what can be called a “compiler belt”. The compiler belt is a substantially flexible belt that hangs loosely from a rotating roll disposed over the compiler tray. The hanging compiler belt can contact the topmost sheet in the compiler tray, and by its rotation, can push the topmost sheet toward the backstop, thus ensuring that each sheet is aligned against the backstop prior to stapling.

With higher-speed printers and copiers, it is known to provide a system to “buffer” sheets as they emerge from the print engine; that is, in order to accommodate the timing of an operation done by the finisher, such as stapling and ejection of a set, sheets emerging from the print engine at a substantially even rate are temporarily withheld from the finisher until the finisher is ready to accept them. As a practical matter this means that, following a finisher operation during which sheets from the print engine are buffered or withheld, a small stack of sheets are sent to the finisher, instead of the usual one sheet at a time. If a stack of multiple sheets is collected in the compiler tray, there may be a problem of ensuring that all of the sheets in the stack are aligned against the backstop prior to stapling.

SUMMARY

There is provided an apparatus and method for interacting with sheets. A sloped compiler tray receives sheets and includes a backstop at a lower edge thereof. An upper compiler member is positioned to contact a top sheet retained in the compiler tray, and is movable to convey the top sheet toward the backstop. A lower compiler member is positioned to contact a bottom sheet retained in the compiler tray, and is movable to convey the bottom sheet toward the backstop.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 are a series of simplified elevational views showing the structure and operation of a compiler-stapler.

DETAILED DESCRIPTION

FIGS. 1-4 are a series of simplified elevational views showing the structure and operation of a compiler-stapler. Sheets, such as emerging from a buffer (shown schematically as 99) downstream of a print engine such as an electrostatographic print engine (shown schematically as 98) are ejected from a chute 10, pushed by roll pair 12. It is generally intended that the sheets, which have been buffered to form a sheet stack SS, fall into the uphill compiler tray 20, and align themselves against backstop 22. As shown in FIG. 1, right after the sheet stack SS emerges from chute 10, the sheets therein are stacked, but not aligned. In the illustrated case, sheet stack SS includes three sheets, and the middle sheet of the stack trails the other sheets. This is a typical artifact of one type of buffering method, although different types of buffering methods will cause different sheets in the stack to trail the others.

Because of the coefficient of friction between adjacent sheets within a stack, when a stack of sheets SS is deposited into an uphill compiler tray, all of the sheets in the stack SS may not successfully slide downward to be aligned against backstop 22, with the result that the sheets in stack SS will not be suitably aligned, such as for stapling by a stapler 24.

FIG. 2 shows the sheet stack SS after it has fallen, largely by gravity, into compiler tray 20 and toward backstop 22. There is provided in this embodiment a compiler flapper 26 as well as an eject flapper 28. The compiler flapper 26 is disposed close to the backstop 22 (such as 1-2 inches) and rotates in a direction so that it will contact the top sheet in stack SS and thus draw the top sheet toward the backstop 22. A functional equivalent to the compiler flapper 26 would be a hanging compiler belt, such as described with reference to the patents mentioned above: as used herein, a flapper, compiler belt, roll, or other movable member in contact with the top sheet can be considered an “upper compiler member.” An effectively flexible member, such as a flapper or hanging belt, provides roughly the same amount of drive allowing for variations in the stack height on compiler tray 20.

While the compiler flapper 26 acts to push the top sheet of stack SS toward backstop 22, another roll, lower compiler roll 30, is positioned to contact the bottom sheet in the stack SS and draw it toward the backstop 22. As shown, lower compiler roll 30 is mounted so that a portion of the circumference thereof emerges through an opening in the compiler tray 20. As used herein, a belt, roll, or other movable member in contact with the bottom sheet can be considered a “lower compiler member”. One possible variation on the illustrated lower compiler roll 30 is a three-legged flapper, which in some orientations would not broach the surface of complier tray 20; other relatively flexible rollers may provide practical advantages for lower compiler roll 30 in specific designs.

When the sheet stack SS is in the position shown in FIG. 2, the compiler flapper 26 engages the top sheet of the stack and the lower compiler roll 30 engages the bottom sheet of the stack, both drawing the stack SS toward the backstop 22. As shown in FIG. 3, the second or middle sheet in stack SS, because it had been trailing the other sheets when the stack SS was first emitted from the chute 10, is first to contact backstop 22. The middle sheet is driven towards the backstop due to the friction between it and the top and bottom sheets. The compiler flapper 26 and the lower compiler roll 30 then continue to draw the top and bottom sheets respectively toward the backstop 22, until all three sheets are aligned against backstop 22, as shown in FIG. 4.

When all of the sheets in stack SS are aligned against backstop 22, then the stack, along with any further sheets that are emitted from chute 10, can be stapled, if desired, by stapler 24. The compiled or stapled set of sheets can then be ejected at once from the compiler tray 10 by an ejection roll 32, although other devices such as “kickers” may be provided for ejection as well. During the ejection step, lower compiler roll 30 may be disengaged, so as not to interfere with the ejection, or even caused to rotate in a direction suitable for ejection of a set from compiler tray 20.

The various rollers, flappers, and other hardware shown in the Figures would, in a practical application, be driven by controllable motors as coordinated by a control system, as is generally familiar in the art of finishers, and which is generally illustrated as 100. There may also be provided any number of electromechanical and/or optoelectronic sensors (not shown) to detect positions of sheets and other parts in the illustrated apparatus; these sensors can be used to provide data to the control system operating the hardware.

Although the illustrated series of steps shows what happens when a stack of three buffered sheets enters the compiler-stapler, the apparatus can be controlled to operate differently when single sheets are entering the compiler, one at a time. For example, and depending on a specific implementation, when single sheets are emitted from chute 10 and deposited in compiler tray 20, the lower compiler roll 30 can be allowed to roll freely and the flapper 26 can be stopped. Determining whether single sheets or a stack of sheets are being emitted from chute 10 at a given time can be done by control system 100 by monitoring the behavior of the buffer 99, or by determining that a stack of sheets has been ejected from compiler tray 20. Also, it may be functionally important to operate the hardware in a certain way if the stack is known or determined to have three or more sheets therein: a stack having three or more sheets will have a top sheet, bottom sheet, and one or more middle sheets.

The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. 

1. An apparatus for interacting with sheets, comprising: a sloped compiler tray for receiving sheets; a backstop at a lower edge of the compiler tray; an upper compiler member positioned to contact a top sheet retained in the compiler tray, the upper compiler member being movable to convey the top sheet toward the backstop; and a lower compiler member positioned to contact a bottom sheet retained in the compiler tray, the lower compiler member being movable to convey the bottom sheet toward the backstop.
 2. The apparatus of claim 1, further comprising a buffer for conveying a stack of sheets into the compiler tray.
 3. The apparatus of claim 1, further comprising a print engine for outputting sheets to the buffer.
 4. The apparatus of claim 3, the print engine outputting sheets at a substantially regular frequency.
 5. The apparatus of claim 1, further comprising a control system for determining that a stack of sheets are being conveyed to the compiler tray.
 6. The apparatus of claim 5, the stack including at least three sheets.
 7. The apparatus of claim 1, the upper compiler member including a flapper.
 8. The apparatus of claim 1, the lower compiler member including a roll.
 9. The apparatus of claim 8, a portion of the roll being disposed through an opening in the compiler tray.
 10. The apparatus of claim 1, further comprising a control system to stop moving the lower compiler member to convey the bottom sheet toward the backstop, when the stack of sheets is being ejected from the compiler tray.
 11. The apparatus of claim 1, further comprising an electrostatographic print engine for outputting sheets to be conveyed to the buffer.
 12. The apparatus of claim 1, further comprising a stapler for stapling sheets in the compiler tray.
 13. A method of interacting with sheets, comprising: providing a sloped compiler tray for receiving sheets and a backstop at a lower edge of the compiler tray; moving an upper compiler member positioned to contact a top sheet retained in the compiler tray, to convey a top sheet retained in the compiler tray toward the backstop; and moving a lower compiler member positioned to contact a bottom sheet retained in the compiler tray, to convey the bottom sheet toward the backstop.
 14. The method of claim 13, further comprising conveying a stack of sheets into the compiler tray.
 15. The method of claim 14, further comprising determining that a stack of sheets are being conveyed to the compiler tray.
 16. The method of claim 14, the stack including at least three sheets.
 17. The method of claim 13, further comprising stopping moving the lower compiler member to convey the bottom sheet toward the backstop, when the stack of sheets is being ejected from the compiler tray.
 18. The method of claim 13, further comprising a print engine outputting sheets at a substantially regular frequency; and buffering the sheets from the print engine to form a stack of sheets. 